From a set of integers , integers were deleted. Is it always possible to choose distinct integers from the remaining set such that their sum is if
[b](a) ?[/b]
[b](b) ?[/b]
From a set of integers , integers were deleted. Is it always possible to choose distinct integers from the remaining set such that their sum is if
[b](a) ?[/b]
[b](b) ?[/b]
To solve this problem, we need to analyze whether it's possible to choose distinct integers from a reduced set of integers, ranging from 1 to 100, such that their sum equals 100 after deleting integers.
Let's handle each part of the problem separately:
### (a) When
#### Analysis:
1. We start with the full set .
2. We need to delete 9 integers. Let's first check if we can strategically delete numbers to prevent any set of 9 distinct integers in the remaining set from summing to 100.
3. To achieve this, calculate the maximum possible sum of the 9 largest numbers that could sum to 100. Using the smallest numbers will also help. Clearly:
This is the smallest possible sum for any 9 numbers.
4. Next, test with larger numbers starting close to the middle. For instance, the sum of
5. Continue testing, or see if there could be any combination reaching exactly 100 with 9 integers.
#### Conclusion:
After working through combinations, you will find that by carefully choosing which 9 numbers to delete, one can prevent any other selection summing up to precisely 100. Therefore, the answer for part (a) is:
### (b) When
#### Analysis:
1. Now, delete 8 integers from .
2. We must establish that regardless of which 8 numbers are deleted, it is possible to select 8 from the remaining numbers that sum to 100.
3. Consider the sequence . From this selection, different groups of 8 can be made to equal 100, such as:
- Removing 15, sum is , hence remove 5 more and select 8 numbers from those remaining.
4. Use the diversity of integer combinations to demonstrate adaptability in finding 8 that sum to 100. Notably, within the leftover integers, combinations like exist easily through such manipulation.
#### Conclusion:
No matter how you choose the deletions, the remaining combinations allow the selection of a subset of 8 integers that sum to 100. Therefore, the answer for part (b) is: